Tone-arm for phonographs



A. F. BRUHY.

TONE ARM FOR PHONOGRAPHS.

APPLICATION FILED OCT. 18. I9I9.

3 1 364 189. a Patented Jan.4;1921;

nnnnnnnnnnnnnnnn nnnnnnnnnnnnnn cv OFFICE.

ALEXANDER F. BBUHY, O33 \VEST BEND, WISCONSIN, ASSIGNOR TO PLYMOUTH PHONOGRAPH CGMPANY, A CUR'PORATION OF WISCONSIN.

TONE-ARM FOR PHONOGRAPHS.

incense.

Application filed October 18, 1919.

To aZZ whom it may concern Be it known that I, ALEXANDER F. BRUHY, a citizen of the United States, residing at lVest Bend, in the county of lVashington and State of Wisconsin, have invented new and useful Improvements in Tone-Arms for Phonographs, of which the following is a specification.

My invention relates to improvements in tone-arms employed in connection with phonographs or talking-machines, and especially to that particular construction of tonearm in which the same, in addition to being mounted to oscillate upon the base-plate, is spring-balanced so as to support or counterbalance the outer end of the tone-arm carrying the sound-box and thereby prevent the stylus or needle ironi bearing too heavily upon the record and unduly wearing the I-lcretoi'ore. in tone-arms, constructed as described, it has been customary to connect the inner portion oi? the elbow of said arm with a spring-balance, the idea, as stated, being to overcome to a certain extent the weight of the outer free end of the arm and the soundbox, so that the stylus or needle traveling in the groove of the record will not subject the same to undue wear. I have found, however, that the weight of the tone-arm and consequently the bearing pressure of the needle in the groove of the record should vary to produce the best results from diiierent'makes of records, thus vertically cut records requiring more pressure than those laterally out, and even some records of these two classes will be found to give better results if the pres sure is regulated somewhat.

The ob ects, therefore, of my invention are to produce means for quickly, easily, and accurately adjusting the weight and consequently the pressure of its stylus or needle upon the record, and to this end my invention consists in providing means for adjusting the counter-balancing spring heretoiore employed in the class of tone-arms referred to.

Referring to the drawing 5 Figure l, is a top-plan view of a spring balanced tone-arm having my invention applied thereto, the outer end of the arm being broken away;

Fig. 2, is a side elevation and part1a-l sectional view of the same;

Fig. 3, is a rear elevation thereof; and

Specification of Letters Patent.

Patented Jan. 4, 1921.

Serial No. 331,591.

Fig. 4, shows a modified construction that may be employed in lieu of that shown and which will accomplish the same purpose.

S milar numerals of reference indicate similar parts in all the figures of the drawing.

1 designates the conventional form of tone-arm such as referred to heretofore, the same having formed at its lower end a spherical portion 2 which is supported for oscillation, both vertically and horizontally, by the usual means in the base-ring 3, it being understood that the latter is supported in the usual manner upon the motorboard, not shown.

From the rock-shaft 4, there extends rearwardly a rock-arm 5, the outer or rear end of said arm being engaged by the lower end of a light coiledspring 6, the upper end of which is made fast to some point within the tone-arm above and in rear of the rockshaft 4.

l n the present instance, I provide the rear portion of the elbow of the tone-arm, at a point above its lower end, with a vertical extension 7, the same extending some distance above and below the wall of the arm, and bored longitudinally, as at 8, throughout its length. Within the bore of the projection I mount for vertical movement, an adjusting-rod 9, the same being somewhat longer than the extension and therefore extending above and below the same. The upper end of the extension 7, is, in this. instance, inclined on one side to form a camsurface 7*, for a purpose hereinafter apparent.

The lower end of said rod 9 is connected to the upper end of the before-mentioned coiled-spring 6, and the upper end of this rod may have threaded thereon an adjusting-nut 10, preferably formed with a trans verse kerf 11, so as to be readily rotated by a screw-driver, whereby coarse adjustments of the rod may be obtained, or, if preferred, there may be substituted for the nut, 10 an integral head. i

Between the nut 10 and the cam-face 7 of the projection 7, is an adjustingplate or the name edge of an adjusting-plate 14, positioned upon the tone-arm a short distance in advance of the parts just described, or otherwise supported, as may be preferred. This plate may be plain and have subdivisions indicated thereon, but is preferably formed at intervals with shallow notches 15, the number of such being in accordance with the number of adjustments required to secure the best results while the machine is ope *ating upon records of different makes and styles. To retain the handle 13 in its adjusted position, ll may provide the same upon its underside with a detent 13, adapted to engage any one of said notches.

The operation will be readily understood from the foregoing description, and may be briefly stated as follows: In order to increase or decrease the tension of the spring 6, it is simply necessary to vibrate or swing the operating-handle 13 to the right or left, the latter movement of the handle serving to elevate the adjusting-rod, by means of the coacting cam-surfaces 7 and 13, whereby, as will be apparent the tension of the spring will be increased in accordance with the distance said handle is rotated, while the former movement or that to the left, will have a reverse effect. By increasing the tension of the spring 6, it will be obvious that the combined weight of the tone-arm and sound box will be more nearly counterbalanced, so

that the stylus carried by the sound-box will bear very lightly upon the record, as is required. in order to obtain the best results from all records produced by lateral cut.

On the other hand, those records produced by the vertical cut method, require a deeper penetration of the stylus or needle, and this is obtained by utilizing more or less of the combined weight of the tone-arm and soundbOX, to secure which, the operating-handle needs be swung more or less, as the case may be, to the left.

If desired, there may be indicated on the tone-arm opposite the notches 15, or upon the plate in which said notches are formed, of the different makes of records to wh ch said notches apply, so that no experimenting by the operator is required in order ot adjust the machine for playing any particular make or style of cut record.

In the modification illustrated in Fig. 4, it will be seen that l omit the notched plate 14, and in lieu of the operating-handle 13, h retofore described, I cmploy a rearwardly disposed shorter operating-handle 16, extending the same from a cam-plate 17, mounted on the rod 9, under the head or nut 10, as heretofore. The underside of the plate 17, in lieu of being inclined, provided with opposite detents Or ribs 18, adapted to re movably engage with corresponding grooves 19, formed in the upper end of the bored pro ection 7, the latter 1n this instance being squared at its upper end to correspond with the underside of the plate 17. When the detents or ribs 18 occupy the grooves 19, the cam-plate will be flat upon the upper end of the projection 7 and the coiled-spring 6 will be under its lightest or least tension. A slight lateral movement of the handle will, however, serve to cause the detents or ribs 18 to leave the grooves 19 and rest upon the surface of the projection 7 between said grooves, so that, as will be apparent, the plate 17 becomes elevated and serves to raise the adjusting-rod and place the spring 6 under somewhat great-er tension. When thus adjusted the spring will be under its heaviest tension and the machine adapted for operating upon such records as are pro duced by the lateral cut method. While this arrangement provided for only two adjustments, yet it will be suficient, generally speaking, for both lateral and vertical cut records, regardless of their source of manufacture, although finer adjustments, such as provided for in my preferred construction, will be found useful and more effective in producing the very best results from all makes of records to be found upon the mar lret to-day. It will of course, be understood, that in either of the constructions described, the manufacturer will adjust the parts of thedifferent kinds of records, so that all the operator will have to do will be to swing the operating-handle to the point indicated.

Records produced by the lateral-cut method require less pressure of the stylus or needle than do such records as are produced by the vertical-cut method, for the reason that in the first instance the stylus or needle merely follows the lateral undulations while in the second instance the stylus or needle must follow the vertical undulations of the grooves. It is clear, therefore, that any excess pressure in either instance will materially interfere with the best results and also result in undue wear of the grooves of the records.

The importance and the desirability, therefore, of providing an accurate and ready means of adjustment of the weight of the tone-arm so as to regulate the pressure and degree of penetration of the stylus or needle in the grooves of the records being operated upon, cannot be too highly appreciated.

Having described by invention, what I claim, is:

1. The combination with a pivoted and swiveled tone-arm provided in its rear vertical portion with a bored post, the supporting rock-shaft for the tone-arm, the rockarm and spring, of an adjusting rod mounted for reciprocation in the bored post and connected at its lower end to said spring, a head at the upper end of said rod, an operating-handle loosely mounted on the rod helow the head thereof, and means acting upon the handle for raising and lowering the rod when said handle is oscillated.

2. The combination with a pivoted and swiveled tone-arm provided at its rear vertical portion with a bored post, the supporting rock-shaft for the tone-arm, the rock-arm and spring, of an adjusting rod mounted for reciprocation in the bored post and connected at its lower end to said spring, a head at the upper end of the rod, an operating handle loosely mounted on the rod below the head, and an inclined adjusting-plate carried by the tone-arm and disposed in the path of said operating handle, whereby when said handle is oscillated it is caused to ride over the edge of said adjusting-plate and raise or lower said rod.

3. The combination with a pivoted and swiveled tone-arm provided at its rear side with a bored post, the latter having at its upper end an inclined cam-face, and a counterbalancing-spring for the tone-arm, of a reciprocating adjusting rod mounted in the bore of the post and connected at its lower end to the spring, an oscillating handle carried loosely by the upper end of the rod and provided on its underside with a cam-face cooperating with the cam of the post, whereby when the handle is oscillated the rod is raised or lowered by the action of the cams and the tension of the spring decreased or increased.

4. The combination with a pivoted and swiveled tone-arm provided at its rear side with a bored vertical post, a counterbalancing coiled spring for the tone-arm, and a vertically reciprocating rod connected to the spring and mounted in said bored post, of an operating handle extending from the upper end of the rod above the tone-arm, means whereby said handle when merely oscillated will raise and lower the rod and increase or decrease the tension of the spring.

5. The combination with a pivoted and swiveled tone-arm, and a counterbalancingspring for the same, of a bored post in the tone-arm, an adjusting rod threaded at its upper end, mounted in said post and connected to the spring, an adjusting nut threaded on the upper end of said rod above said post, a handle having an eye loosely receiving the rod and bearing at its upper side against the underside of the nut, and means between said eye and upper end ofthe post for causing said rod to raise and lower when said handle is oscillated.

6. In combination, a horizontally swiveled tone-arm having an overhanging end, a spring for counter-balancing said overhanging tone-arm end, a post secured to said tone-arm and having a hole therethrough in alinement with said spring, said post having a cam-portion adjacent to the outer extremity of said hole, an adjusting rod extending through said hole, said rod having its inner end secured to said spring and having a headed outer end, an adjusting element having a cam-portion coacting with said post cam-portion and having an opposite portion reacting against said rod head, and means for oscillating said adjusting element relatively to said post to vary the tension of said spring.

ALEXANDER F. BRUHY. 

